Any chemists want to take a guess what happened?

[TheStrand]

Hi, I've been making soap for nearly a year, mostly for personal use but experimenting for possible craft product sales. I've been trying many different things to try to make a shower type body wash that is viscous enough to not just rinse through your fingers before lathering and washing. Until now I've been using a foam dispenser for liquid soaps that works great, but I'm just stubborn and insist on finding the solution that no one else has.

Part one of the problem is I am trying to make it with Hemp seed oil and Coconut oil (fractionated) as much as possible, since olive oil "Castile" soap isn't very bubbly or cleansing...

Using Glycerin instead of water makes a more viscous soap, so I've come to try to make a Hemp/coconut oil liquid soap with glycerin lye mixture...

Here's the recipe I've attempted this morning for small experimental batch:
250g Hempseed oil
200g Coconut oil (fractionated)
246g Glycerin
123g KOH

Followed the usual process:
Heat oil mixture in small crock
Heat Glycerin to 200 degrees C
Mix KOH with Glycerin
Stir Lye with heated oils
Stick blend mixture

I wound up burning out a stick blender on this batch... (second time I've done that so I'm switching to a drill with pain mixer)

The mix never got past smooth... And now it sits at a runny (natural type) peanut butter consistency after almost two hours of intermittent mixing and cooking.

Glycerin mixes usually go to paste FAST!

Any ideas what has happened here?

 

[TheStrand]

So after roughly 6 hours of heat and infrequent stirring, the bottom started turning into a dark clear liquid. So I'm going to keep at the cooking and see what I wind up with when it stops separating. But if anyone has any ideas as to a better way to thicken a LS based on Hempseed Oil and Fractionated Coconut Oil, please feel free to let me know.

Salting didn't work (As I understand it, that's because there's no Olive oil in this recipe) I've even made a HUGE mess trying to use Xanthan Gum at one point. That was a complete failure that I won't even try to troubleshoot.

 

[ChemicalPyros]

Hello @TheStrand,

For the mixture you have done, I am not sure what happened or how. But to be on the safe side you can put it in a sealed container and leave for a couple of weeks and see what comes out of it. Thermodynamically speaking, soap should come out in the end, but when will that end be it is difficult to say for sure. anyway I recommend that you do not heat any more, because you risk oxidation and the final product will be rancid.

For the thickening, you need oleic acid (which is available a lot in olive oil but can be found in other oils such as avocado oil, sunflower oil, high oleic sunflower oil, ...), and you need your oleic acid to be above 50% in order to thicken it with salt (any salt containing sodium ions can do such as sodium chloride, EDTA, ...) of course different salts will give different thickening. On a more personal note, I use sodium chloride to thicken LS for personal use, and EDTA to thicken LS for dishwashing and other cleaning purposes.

It is a common misconception to use xanthan as a thickening agent, while it is said that it is compatible with basic solutions, it is not when potassium salts are present. The go to thickeners are usually cellulosics (CarboxyMethyl Cellulose, HydroxyPropylMethyl Cellulose, HydroxyEthyl Cellulose, ...), they have the added advantage of enhancing the foam in a very noticeable fashion (they make my pure olive oil LS foamy). Of course the LS should be done in water.

 

[TheStrand]

Thank you, this is also very helpful information. The majority of tutorials I went through when I started to learn about soap making focus on the cooking process, so the entire idea of not using heat straight to the end is a bit alien to me. I'm going to start trying other processes going forward.

By diluting this batch exclusively with glycerin, I was able to keep it at a thick enough consistency to work, but now I have to find a way to increase it's bubbly/lather. I was considering going back with another experiment just increasing the coconut oil percentage to see if that would improve the bubbly lather, but what you're saying about how cellulose improves the foam sounds like a much better and perhaps cheaper way of achieving my end goal.

Again, thank you for sharing! This was very helpful and I will be using it in my continued experimentation.

 

[ChemicalPyros]

In chemistry it is very well known and established that heat accelerate a reactions rate, so no question here, it is actually one of the earliest established laws in chemistry (ask Le Chatelier). The real question is what reaction(s) is the heat accelerating. In the case of oils you may have lots of variables, such as the state of the oil, is it refined or not, if it is refined then it means that it is purely a mixture of fatty acids, if not then you have the unsaponifiables to take into account. If you go with refined you have two reactions, the saponification and the oxidation, the more unsaturated fatty acids the more prone to oxidation the fatty acids will be. If you go with unrefined then you have a plethora of reactions that may occur and all are accelerated by heat.
What does this mean on a macroscopic scale (or from a user point of view)? too much heat may lead to bad smell (rancidity from the oxidation of the fatty acids), or to darker colors which may not be appealing to certain customers (from burning unsaponifiables), and of course a shorter shelf-life. Another loss when burning the unsaponifiables is the loss of some active ingredients such as natural vitamin E, phenols and other molecules that may be beneficial to the skin.
Personally I prefer to make my soaps via cold process of course there are exceptions, so please consider this are as a mere recommendation that you may or may not take into account.

I understand your frustration concerning the thickness of the LS, because I went through the same road once.
While making LS in glycerin is a great achievement (non aqueous reactions are always considered special in chemistry) it is relatively costly and difficult to control especially if you are not in a laboratory setting (or highly controlled environment).
I recommend that you do the saponification reaction in water and if you do it at room temperature or heat a little bit (better not above 40 - 45 degrees Celsius) it should take between 24 to 72 hours to complete. Then you take the water you want to dilute with and add the thickener and hydrate it completely, finally you add the potassium soap you made and you mix till total dissolution.
If you want to go exotic, you can replace the diluting water with coffee, tea, beer, wine or even milk, but here you need to take into account the risk of bacterial/fungal contamination so may need to consider adding a preserving system.
A small trick that could enhance greatly your foam is adding 1 to 2% sugar to the final LS mixture (any sugar will do, but if you add beer/milk/wine they already contain sugars so no need).

 

[TheStrand]

Hello @TheStrand,

For the mixture you have done, I am not sure what happened or how. But to be on the safe side you can put it in a sealed container and leave for a couple of weeks and see what comes out of it. Thermodynamically speaking, soap should come out in the end, but when will that end be it is difficult to say for sure. anyway I recommend that you do not heat any more, because you risk oxidation and the final product will be rancid.

For the thickening, you need oleic acid (which is available a lot in olive oil but can be found in other oils such as avocado oil, sunflower oil, high oleic sunflower oil, ...), and you need your oleic acid to be above 50% in order to thicken it with salt (any salt containing sodium ions can do such as sodium chloride, EDTA, ...) of course different salts will give different thickening. On a more personal note, I use sodium chloride to thicken LS for personal use, and EDTA to thicken LS for dishwashing and other cleaning purposes.

It is a common misconception to use xanthan as a thickening agent, while it is said that it is compatible with basic solutions, it is not when potassium salts are present. The go to thickeners are usually cellulosics (CarboxyMethyl Cellulose, HydroxyPropylMethyl Cellulose, HydroxyEthyl Cellulose, ...), they have the added advantage of enhancing the foam in a very noticeable fashion (they make my pure olive oil LS foamy). Of course the LS should be done in water.

While looking for a supplier of the cellulose varieties you mentioned. I came across one for HEC (Hydroxyethyl Cellulose) so far and most for MCC (Microcrystalline Cellulose), would MCC work the same? I definitely don't understand the chemical differences between the varieties and the prices are all over the place. My favorite suppliers don't carry any cellulose powders.

 

[ChemicalPyros]

The difference is mainly with the compatibility with the surfactants, HPMC is more tolerant of hydrophobic surfactants, HEC less so, CMC even less.
I am not familiar with MCC but if you can get your hands on HEC you're in for a treat.
I usually recommend HPMC for the best foam but HEC will do just fine.

 

[smcarroll2020]

Hi. I replicated your formula in the calculator and a couple of this caught my eye:
I wonder if :
1,) liquids:

• for the lye liquid: 1 part water:1part glycerin: 1 part lye would be better. I'm not sure what you are trying to achieve with 2 parts glycerin: 1 part lye. Glycerin is an accelerant, as is the high temp. I know that glycerin method causes soap paste to form fast, so maybe it seized?
• final dilution. it's not uncommon to do a 35% soap to 65% water after trace and the paste has cooked. I don't seem to see a planned dilution amount?

2.) I think you ended up with a tar like gloop because not enough stearic or palmitc acid, perhaps? maybe use coconut oil 76 degree and less of the fractionated oil?
3.) for thickening

• oleic, linoleic, linolenic oils can increase viscosity. this might be an interesting experiment. for later, but maybe increase oleic acid oils?
• the salt method can be tricky. might want to try dual lye method first? maybe 10% naoh: 90% koh
• adding gum after product has cooled can work. some gums have a negative or positive charge, so you'll want to research which is right for your batch. i seem to remember guar, or one of the common gums, has a positive charge. If salt is present, which is a neg, charge, maybe they're butting heads?

I'm going to go out on a limb and say the recipes property chart is incorrect, and the cleaning and bubbly properties are incorrect.

The fatty acid % chart is correct. cleansing is based upon the amount of myristic and lauric acid, as is bubby.
recipe lauric 1 + myristic 0 = 1 the cleansing property would be very low, yet chart reports it as high? This means this soap will not bubble very mush, nor will there be creamy foam.

I think the entry for fractionated coconut oil (FCO) in the oils table is wrong

note the addition of lauric + myristic for the other types of coconut oil is correct (48+19 = 67). for the fco, it should be 2+ 1 = 3, NOT 100!